Discharge tube



Feb. 6, 1934. w. H. T. HOLDEN DISCHAARGE TUBE Filed Nov. 8, 1932INVENTOR 1 EZFoldn ATTORNEY Patented Feb. 6, 1934 DISCHARGE TUBE WilliamHenry Towne Holden, Brooklyn, N. Y., assignor to American Telephone andTelegraph Company, a corporation of New York Application November 8,1932. Serial No. 641,'796

3 Claims.

*This invention relates to electrical discharge devices, and moreparticularly to that class of discharge devices containing a gaseousfilling, such for example as a monatomic gas or metallic vapor, at areduced pressure, and provided with a cathode, control electrodes and ananode so arranged that variations in potential of the control electrodecause corresponding variations in anode current.

such devices have been described in the past, and have ordinarilyrequired either a heated thermionically emitting cathode or an auxiliarymercury arc, the cathode of which also serves as the cathode of thecontrolled current. It is one of the objects of this invention tosubstitute a glow discharge between cold electrodes for the arcdischarge between a thermionic or mercury pool cathode and the auxiliaryanode, which is also employed. But by utilizing a cold cathode :godischarge I am enabled to so arrange the electrodes that a materiallySimpler Construction is possible, avoiding the difficult Constructionrequired in the mercury are type of amplifier. Other objects andfeatures of this invention will become apparent from the followingdetailed description of the invention.

The invention may be more ully understood from the following descriptiontogether with the accompanying drawing in the Figs. 1, 2, 3, 4, and 5 ofwhich the invention is illustrated. Figs. 1 and 2 show the Constructionof control electrode assemblies. Fig. 3 shows a plurality of controlelectrode assemblies mounted on a single stem. Fig. i shows thearrangements of Fig. 3 sealed into a tube. Fig. 5 is a cross-section ofFig. 4.

` Similar reference characters have been utilized to denote like partsin all of the figures.

Referring to the appended drawing, Figures l and 2 illustrate theConstruction of a control electrode assembly. A glass tube l is sealed Habout anode lead 2 at its upper end. A errule 4 to which grid lead 3 isattached surrounds the upper end of this seal. At the top of the sealand fitting tightly against the end of the glass is anode 7. Lead wire 2is carried through the anode and welded thereto at the top, forming athe grid meshes. Electrons, however, will pass freely into the interiorof the hollow cylind rical grid structure and reach anode 7. The numberof electrons thus reaching anode '7 may be, controlled by the potentialof grid 6. The space between anode 7 and grid 6 is of such dimensione'that it is small Compared with the mean free path of an electron in thegas at the pressures employed. Positive ions will, therefore, not beormed inside grid 6 and the current to anode 7 will be purely electronicand continuously controllable by the potential applied to grid 6.

The electrode assembly of Figs. 1 and 2 may be immersed in the positivecolumn of a glow discharge by being sealed inside of a tube containing amonatomic gas and a cathode and anode with a suitable source ofpotential connected between them. Any desirable type of discharge tubemay be used.

A plurality of the control electrode assemblies may be supported on asingle reentrant stem 9,

adapted to be sealed into a bulb 14, as shown in' Figs. 3 and 4. Each ofthese electrode assemblies 10, 11, 12 and 13 has its own grid and anodeleads. Fg. 4 shows how a stem such as that of Fig. 3 may be sealed intoa bulb 14, into the other end of which has been sealed a stem 16,carrying a cathode 15 and an auxiliary anode 17, the latter being onlyvisible in the Fig. 5 which represents a cross-section of the bulb shownin Fig. 4 along the section line 1-1. Projections 20 from the interiorof cathode 15 shield the grids of the electrode assemblies 10, 11, 12and 13 from each other.

An auxiliary source of potential applied by conductors 18 and 19 betweenanode 17 and cathode 15 respectively maintains a glow dischargetherebetween, and in such a manner that the electrode assemblies 10, 11,12 and 13 are immersed in the positive column thereof. Each of the saidassemblies, consisting of a grid and anode, together with the commoncathode constitute a threeelement amplifier, and may be usedindependently, in cascade, or in parallel as required, if suitable inputand output crcuits be provided and if the anodes of these electrodeassemblies be supdischarge between cold electrodes. As is well known,the positive column of an arc discharge and of a glow discharge aresubstantially alike in properties, and it therefore is evident that theprinciples of this invention may be applied to a tube in which theauxiliary discharge, from which the electron current for the controlanode is obtained, is maintained between a hot cathode and a cold anode.Referring to Fig. 5, if 1'7 be assumed to be a thermionically emittinghot cathode and 15 the anode of the auxiliary discharge, it is obviousthat this device will operate in the manner already described, when thecathode is heated to an emitting temperature and an arc is maintainedbetween the said cathode and anode.

While the invention has been disclosed as embodied in certain specificforms which are deemed desirable, it is understood that it is capable ofembodiment in many and other widely Varied forms without departng fromthe spirit of the invention as defined by the appended claims.

What is claimed is:

1. A gas-filled discharge tube comprising a plurality of electrodeassemblies supported inside of said tube, each of said. electrodeassemblies comprisng an anode and a grid completely enclosing saidanode, and means for starting a glow discharge in said tube in which allof said electrode assemblies will be immersed.

2. A gas-filled discharge tube comprising a plurality of electrodeassemblies supported inside of said. tube, each of said electrodeassemblies comprising an anode and a grid completely enclosing saidanode, means for starting a, glow discharge in said tube in which all ofsaid electrode assemblies will be immersed, and means for shielding thegrids of said electrode assemblies from each other.

3. A gas-filled discharge tube comprising a plurality of electrodeassemblies supported inside of said tube, each of said electrodeassemblies comprising an anode and a grid completely enclosing saidanode, a cylindrical cathode surrounding all of said electrodeassemblies, a cylindrical auxiliary anode coaxially placed with respectto said cathode whereby a glow discharge may be maintained in said tubein which all of said electrode assemblies will be immersed, andelectrostatic shields between said electrode assemblies.

WILLIAM H. T. HOLDEN.

